Field of Invention
This invention relates to a surgical apparatus, especially a kind of anastomat for surgical operation. More specifically, it relates to an improved surgical apparatus actuator.
Description of Related Arts
The working principle of surgical anastomat is to clamp tissues through the closing of two corresponding jaws (which are normally called nail anvil assembly and nail bin assembly) and then push the metal suturing nails in the anastomat nail bin out for molding and suture tissues together. In some anastomats, a cutter is installed to cut off sutured tissues.
The anastomat with the above functions also includes actuator, intermediate connecting body and controller. The actuator consists of nail anvil assembly, nail bin assembly and drive assembly. The nail anvil assembly includes a nail molding surface which contains multiple rows of nail grooves. The nail groove is used for metal suturing nail molding. The nail bin assembly usually consists of nail bin, suturing nail, nail push block and nail push slide and nail bin seat. The upper surface of the nail bin is the tissue contact surface and the nail bin is installed in the nail bin seat. The nail anvil assembly connects at the near end with the near end of the nail bin assembly in a mobile manner and converts between the opening condition and closing condition. The drive assembly connects with the drive mechanism and is used to convert the triggering operation into actuator closing, triggering and opening operations. Generally, each of the nail anvil assembly and nail bin seat contains also a longitudinal groove. The above longitudinal groove is used to accommodate the drive assembly to allow it to pass. When the drive assembly moves toward the far end of the actuator through the above longitudinal groove, it drives the nail anvil assembly and nail bin assembly to convert from the opening condition to closing condition and drives the nail push slide and nail push block to push out suturing nails for molding in the nail groove of the nail molding surface of the nail anvil assembly. Generally, the drive assembly also includes a cutter, which is used to cut tissues among multiple rows of nail threads after tissues are sutured by suturing nails. The controller is used to control the apparatus operation manually, which usually consists of a fixed handle, a trigger connecting with the fixed handle in a relatively mobile manner and a group of drive mechanisms transmitting the triggering operation to the actuator. The intermediate connecting body connects with the far end of controller in a mobile manner and connects with the near end of the actuator. The intermediate connecting body constitutes a connecting passageway to transmit the triggering operation to the actuator.
The Endo GIA Universal cutting anastomat from Tyco Healthcare in USA (renamed as Covidien later) and the Echelon cutting anastomat from Ethicon Endo-Surgery in USA are the representative products achieving the above functions. The above products have been sold for years and proved by market as having a good clinical application effect. The actuators of the blue nail bins of the above products can compress human body tissues (such as stomach tissues, lung tissues, intestine tissues, etc.) from a natural thickness of 5 mm-8 mm to a closing thickness of 1.5 mm when the nail anvil assembly and nail bin assembly close. In terms of the product function, the tissue closing thickness should be uniform from the near end of the nail anvil to the far end thereof so as to ensure suturing nails to be highly uniform in molding. Suturing effect can be guaranteed only when suturing nails suture tissues with a stable quality. Therefore, the nail anvil assembly needs to have a high bending strength. In nail anvil assembly manufacturing, the nail groove has a substantial material displacement in mould punching molding and this objectively requires that the material of the nail anvil assembly has good flowability and is easy to create a large-scale plastic deformation. The requirements of the nail anvil assembly for material plasticity and bending strength are contradictory. The technical proposals adopted by the Endo GIA Universal cutting anastomat and the Echelon cutting anastomat solve the above contradiction satisfactorily. However, there are still places requiring perfection, for example: the bending strength of the nail anvil assembly of the Endo GIA Universal cutting anastomat is still not high enough in some clinical applications and the processing technology is highly difficult; the bending strength of the Echelon cutting anastomat is enough, however, the processing technology is complicated with a high cost.
For example, in U.S. Pat. No. 5,865,361, Tyco Healthcare described the nail anvil assembly of the Endo GIA Universal cutting anastomat. By referring to the description in U.S. Pat. No. 5,865,361 and combining with the design adopted for the real product being sold on market, the nail anvil assembly is welded from nail anvil plate and back cover plate. The empty cavity formed between the upper surface of the back cover plate and the nail anvil plate is the space for cutter holder pin to slide. The function of the back cover plate is to prevent tissues from being injured as a result of pinching by the cutter holder pin in the process of the nail anvil assembly closing tissues and anastomosing. The back cover plate is punched from 0.2 mm-0.3 mm thick stainless steel sheet. The nail anvil plate is punched from stainless steel sheet around 1 mm thick. Both the two spare parts use 304 stainless steel which can be strengthened through heat treatment and can exhibit a conspicuous machining hardening in the process of machining. On the lower surface of the nail anvil plate, a lot of nail grooves formed from cold punching process are distributed. For the Endo GIA Universal nail anvil plate with a 45 mm nail thread specification, 6 rows×11=66 nail grooves with a depth around 0.5 mm are punched (coldly) on the 45 mm×9 mm plane. The nail groove depth reaches half of the nail anvil plate material thickness. This results in the surface of material that the nail anvil plate and the mould punch top contact having serious machining hardening in nail groove cold punch molding, which prevents nail grooves from further molding and also results in aggravated wearing to the mould punch and mould life reduction and thus results in greater nail groove dimension fluctuation, accuracy reduction and eventual influence on the suturing nail molding quality.
With regard to the above difficulties in nail groove molding, it is speculated that in manufacturing the nail anvil plate of the Endo GIA Universal cutting anastomat, the nail anvil plate uses 304 stainless steel sheet in annealed state to reduce maximally the initial material hardness, upgrade the nail groove molding accuracy and mould life. However, the bending strength of the nail anvil plate made of 304 stainless steel in annealed state is reduced and that thus results in the bending strength of the nail anvil assembly being low. As a result, when that product is applied to some thick tissue anastomosing and cutting occasions, the nail anvil assembly has a serious bending deformation after the nail anvil assembly and nail bin assembly close. As a result, it is unable to ensure the tissues clamped in the jaw to be consistent in compression thickness. Especially, the tissues at the far end of the jaw have an unsatisfactory closing effect due to incomplete compression. This results in tissues being easy to overflow toward the far end of the jaw in cutting and the tissue width after anastomosing being greater than the original tissue compression length. In some cases, it may result in having to increase the amount of nail bins, which implies the increase in medical cost; when serious, it may result in poor suturing nail molding.